A point-to-point radio link is a communication system for transmission of data between two fixed locations, or sites, over a point-to-point link. Point-to-point radio links often operate at microwave carrier frequency, i.e., in the GHz range. A radio link transmitter and receiver are often incorporated into one unit, herein denoted as transceiver. Radio links often use directive antennas in order to improve communication conditions. Such directive antennas must be carefully aligned with respect to a corresponding antenna at the other side of the radio link in order to provide maximum system gain. Radio link antenna deployment therefore takes time and often requires skilled personnel in order to properly deploy antennas.
Directive antennas, including mounting brackets for attaching antennas to fixed infrastructure, must often be assembled from a kit of parts on-site, and then carried manually or lifted high above ground before reaching the deployment point. Parts may get lost in the process, causing further delays.
FIG. 1 illustrates a radio link system implementing line-of-sight (LOS) multiple-input multiple-output (MIMO) communication according to prior art. A first MIMO transceiver TRX A communicates 110 with a second MIMO transceiver TRX B, at a carrier frequency f, via a first 101 and a second 102 antenna spaced apart by distance d1. The second MIMO transceiver TRX B uses two antennas spaced apart by distance d2. A LOS-MIMO system provides increased system spectral efficiency compared to single-input single-output (SISO) systems, in terms of bits/sec/Hz. However, in order for a LOS-MIMO system to be fully functional, the inter-antenna distances d1 and d2 must be carefully configured as a function of radio link length L and carrier frequency f.
LOS-MIMO antenna deployment presents an even bigger challenge than conventional radio link antenna deployment, since LOS-MIMO requires a plurality of antennas, which antennas must be located at certain relative positions to each other. FIGS. 2a and 2b illustrate examples of LOS-MIMO antenna deployments. It is often difficult to adjust inter-antenna distances, e.g., by adjusting location of mounting brackets 230 when antennas are deployed high up in a mast 210, such as illustrated in FIG. 2a, or on a building wall or roof-top 260, such as illustrated in FIG. 2b. 
WO/2013/097888 relates to a LOS-MIMO system which offers simplified antenna deployment. Here two antennas are arranged on a shared mounting bracket and adjustably in relation to each other such that the inter-antenna distance can be adjusted without adjusting the position of the mounting bracket. Thus, LOS-MIMO antennas need only be attached to the mast or building once, and then the mounting bracket need not be moved during inter-antenna distance adjustment. This arrangement comprises a number of moving parts and is thus associated with some additional manufacturing cost.